1. Field of the Invention
The present invention relates to a power converter, and more particularly to a control circuit of switching power converters.
2. Description of the Related Art
The high current demand normally decreases the power efficiency in the power converter. The power loss of the power converter is exponentially proportional to its current.PLOSS=I2×R  (1)
where I is the switching current of the power converter; and R is the impedance of the switching devices such as the resistance of the inductor and the transistor, etc. Therefore, parallel technologies had been developed to reduce the power consumption of high current power converters in recent development. Such as “Multi-phase converter with balanced currents” by Walters et al., U.S. Pat. No. 6,278,263; “Multi-phase and multi-module power supplies with balanced current between phases and modules” by Yang et al., U.S. Pat. No. 6,404,175. However, the problem of these prior arts is extra power losses caused by the current measurement of the current balance. Another disadvantage of prior arts is the inflexibility of parallel power channels. The object of present invention is to overcome foregoing problems. A switching controller is developed for the parallel of power converters. The number of parallel channels is not limited theoretically. Synchronization and phase shift of the switching are designed to spread the switching noise and reduce the ripple. Power sharing technology is used to replace the current balance. No current measurement is needed, which simplifies the control circuit and improves the efficiency of power converters.